Bonding of an upper and a shell in a shoe

ABSTRACT

A shoe upper and a shoe shell are attached to one another by molding. The upper is placed on a mold core, which includes a portion resembling a foot and a portion on which the upper fits. A flap provided on the upper extends along at least a portion of a bottom rim of the upper and has opposing interior and exterior sides. A mold is provided around the mold core and the flap so as to define a cavity between the mold and the mold core. The flap extends into the cavity so that both the interior and exterior sides of the flap are exposed within the cavity. A shell material is introduced into the cavity so as to mold the shell material directly around the mold core portion resembling a foot and to cohere the shell material to both the interior and exterior sides of the flap.

TECHNICAL FIELD

This disclosure relates generally to shoes and more particularly to bonding of an upper and a shell in a shoe.

BACKGROUND

Shoes provide an important barrier between our feet and the physical world. In many circumstances, such as cold-weather environments, a waterproof shoe is desirable. However, the consumer market for shoes is a highly competitive market, in which buyers demand low prices. Thus, additional shoe features, such as waterproofing, will not lead to commercial success, unless those features can be provided affordably. Because making shoes is a labor-intensive activity, costs are most effectively contained by minimizing the amount of labor needed to add new features to shoes.

SUMMARY

According to one method, a shoe shell is attached to a shoe upper by molding. The upper is placed on a mold core, which includes a portion resembling a foot and a portion on which the upper fits. A flap provided on the upper extends along at least a portion of a bottom rim of the upper and has opposing interior and exterior sides. A mold is provided around the mold core and the flap so as to define a cavity between the mold and the mold core. The flap extends into the cavity so that both the interior and exterior sides of the flap are exposed within the cavity. A shell material is introduced into the cavity so as to mold the shell material directly around the mold core portion resembling a foot and to cohere the shell material to both the interior and exterior sides of the flap.

According to another method, a shoe shell is attached to a shoe upper without stitching. The upper has opposing interior and exterior sides and a bottom periphery rim for attachment to the shell. The shell has a top periphery rim, which coheres to portions of both the interior and exterior sides of the upper in proximity to the bottom periphery rim of the upper.

A shoe may be made in accordance with either method described in the preceding paragraphs. Regardless of its method of manufacture, a shoe comprises an upper and a shell. The upper has opposing interior and exterior sides and a bottom rim. The shell has an upper rim, which coheres to at least portions of both the interior and exterior sides of the upper in proximity to the bottom rim of the upper, without stitching of the upper to the shell. As used herein, the term “shoe” encompasses all types of footwear, including, for example, boots.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a shoe upper on a mold core, according to one embodiment.

FIG. 2 is a side cross-section view of a mold being placed around a portion of the shoe upper and mold core of FIG. 1.

FIG. 3 is a partial cross-section view of a shoe shell formed within the mold of FIG. 2.

FIG. 4 is the shoe of FIG. 3 in the process of being removed from the surrounding mold.

FIG. 5 is cross-section view of toe portion of the shoe, mold core, and mold of FIG. 3, taken along line 5-5 of FIG. 3.

FIG. 6 is an enlarged cross-section view of a bond between the upper and shell of the shoe of FIG. 3, according to a first embodiment.

FIG. 7 is an enlarged cross-section view of a bond between the upper and shell of the shoe of FIG. 3, according to a second embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to the above-listed drawings, this section describes particular embodiments and their detailed construction and operation. As one skilled in the art will appreciate, certain embodiments may be capable of achieving certain advantages over the known prior art, including some or all of the following: (1) attachment of a shoe shell to an upper without stitching; (2) a waterproof interface between a shoe shell and an upper; (3) simpler and less expensive construction; and (4) greater design freedom by relaxing restrictions on permissible curves and angles imposed by a stitching allowance. These and other advantages of various embodiments will be apparent upon reading the following.

FIGS. 1-4 illustrate steps of a method for assembling a shoe according to one embodiment. Generally, that method comprises placing a shoe upper on a mold core, placing a mold around portions of the upper and mold core, molding a shell material between the mold and the mold core to form a shell cohered to the upper, and removing the mold and mold core after the shell material has solidified in the form of the shell.

As shown in FIG. 1, the first step of the method is to place a shoe upper 100 on a mold core 110. The mold core 110 comprises a top portion 120 generally resembling an ankle and a bottom portion 130 generally resembling a foot. The ankle-like top portion 120 and the foot-like bottom portion 130 may be separate or integral. Although the mold core 110 is preferably solid, that need not be the case; the mold core 110 may be an inflatable bladder, for example. The mold core 110 is preferably formed of metal, such as stainless steel, which can be exposed to high-temperature molding materials without significant deformation or deterioration.

The upper 100 may be any material suitable for a shoe upper, such as natural leather, synthetic leather, a textile, or the like. The upper 100 is preferably waterproof, as the interface between it and a shell (not shown in FIG. 1) below the upper 100 can be made waterproof, as explained below. Examples of waterproof materials suitable for the upper 100 include waterproof leather and textiles with a waterproof membrane or coating, such as, for example, an expanded polytetraflouroethylene membrane commonly sold under the trademarks GORETEX® and EVENT®, or a polyurethane coating. In one form, the upper 100 is a two-ply material of textile on the exterior side and a waterproof membrane or coating on the interior side (although the waterproof layer can be on the exterior side, if desired).

The upper 100 has two opposing sides: an interior side 140 and an exterior side 150. Along the bottom of the upper 100 is a bottom periphery rim 160. The interior side 140 generally fits snugly against the mold core 110, except along the bottom periphery rim 160, which may be more loosely disposed on the mold core 110. Optionally, jigs, pins, pegs, pinchers and wipers, or the like (not shown) can be fitted between the mold core 110 and the interior side 140 of the upper 100 in the vicinity of the bottom periphery rim 160 to separate the upper 100 from the mold core 110 along the bottom periphery rim 160 or portions thereof. Alternatively or additionally, the bottom periphery rim 160 is or comprises a flap of the upper 100. As will be described in greater detail below, that flap is an area of attachment of the upper to a shell (not shown in FIG. 1), which goes around the bottom portion of the mold core 110. The flap may be a stitch flange (although it is not attached by stitching) provided on the interior side 140 of the upper 100 and may extend downward about 8 millimeters (mm), for example.

A next step is shown in FIG. 2, which is a side cross-section view of a mold 200 being placed around a portion of the shoe upper 100 and the mold core 110. In most cases the mold 200 comprises two pieces, such as a front mold piece 210 and a rear mold piece 220, as shown in FIG. 2. Other arrangements for a two-piece mold are possible, e.g., top and bottom pieces, left and right side pieces, etc. Although a two-piece mold offers the advantage of being separable while minimizing the number of joints between pieces, a mold can be formed with three or more pieces. As shown, the front mold piece 210 is moved over the toe portion of the mold core 110 and the rear mold piece 220 is moved over the heel portion of the mold core 110 until mating surfaces 230 abut and preferably engage in a more-or-less sealing contact. Ideally, the mating surfaces 230 are built with sufficient precision to fit together and seal against each other. The mating surfaces may have complementary tongue-in-groove or other surface features to enhance their seal.

When the front mold piece 210 and the rear mold piece 220 contact, they define an interior chamber, in which is typically disposed the mold core 110, or a portion thereof, clad with the upper 100. The interior cavity is defined by an interior wall 240 of the mold 200. A bottom portion of the interior chamber is slightly larger than the foot-like bottom portion 130 of the mold core 110. Thus, when the mold 200 is fully engaged around the mold core 110, there is a cavity or space between the interior wall 240 of the mold 200 and the mold core 110. It is in that cavity where the shell will be formed, as described in further detail below.

Along the interior wall 240 is a ridge 250 positioned to contact and press against the upper 100 somewhat above the flap or bottom periphery rim 160 of the upper 100 when the mold 200 is fully engaged around the mold core 110 clad with the upper 100. The ridge 250 functions to dam the flow of the shell material and retain the shell material in place when it is injection molded, as explained in more detail below. In some cases, it may be helpful to apply an upward force to the mold core 110 and a downward force to the mold 200 to aid in pinching the upper 100 between the mold 200 and the mold core 110 above the flap. (Directional terms, such as “upward” and “downward” are used herein consistently with the orientation of the drawings, to facilitate ready understanding; however, the use of directional terms should not be construed to imply that any particular directional orientation is required; the mold core 110, the upper 100, and the mold 200, for example, may be oriented upside down, sideways, or in any other spatial direction during the manufacturing method; moreover, the directional orientation may change from stage to stage of manufacture.) Alternatively, a gasket or dam may be useful at the external interface between the upper 100 and the mold 200. The mold 200 also preferably has one or more sprues, runners, or flow ports 260 through which shell material can be inserted to form the shell. The number and placement of the flow ports 260 are not critical. The mold 200 is typically made of a metal, such as steel, capable of withstanding the heat associated with an injection molding process.

FIG. 3 shows a partial cross-section view of a shoe shell 300 formed within the mold 200, around the mold core 110, and attached to the upper 100. The shell 300 is preferably formed by injecting a shell material into the flow ports 260. Preferably, the shell material 300 is a deformable or flowable material that can be hardened. An example of one such material is a thermoplastic material, such as, thermoplastic resin (TPR), thermoplastic urethane (TPU), thermoplastic elastomer (TPE), or the like. If necessary, the shell material is heated to a liquid state and then flowed or injected through the flow ports 260, from which it fills the cavity between the interior wall 240 of the mold 200 and the mold core 110. There the shell material 300 is allowed to cool and solidify. During that process, the shell material 300 coheres to both sides of the upper 100 along its bottom periphery rim 160, both sides of which are exposed in the cavity. That cohering is described in greater detail below with reference to FIGS. 6 and 7.

Other types of flowable or deformable material may not require heating to flow. For example, some materials cure or harden upon mixing (e.g., two-part foams, resins, or epoxies), heating, exposure to ultraviolet light, or other environmental conditions. Such materials may be used as the shell material 300.

Although FIGS. 2 and 3 show that the shell material 300 is added after the mold 200 has been placed around the mold core 110, that need not be the order of operations. In some cases, it may be possible to coat either the interior wall 240 of the mold 200 or the sides of the mold core 110 with the shell material before attaching the mold 200 around the mold core 110. It is also possible to provide reinforcement fibers in the cavity between the mold core 110 and the mold 200, in order to augment the structural strength of the resulting shell 300.

FIG. 4 depicts a resulting shoe 400 as the front and rear mold pieces 210 and 220 dissociate from each other and uncover the shoe 400 on the mold core 110. The shoe 400 may undergo additional processing before it becomes a finished product. For example, an outsole 310 (indicated by phantom lines in FIG. 3) may be attached to the bottom side of the shoe 400 underneath the shell 300, and an insole (not shown) may be placed inside and along the bottom of the shoe 400. The shoe 400 can be removed from the mold core 110 by unlacing (or otherwise unfastening) the shoe 400 and then lifting the mold core 110 out of the shoe 400, or by pulling the shoe 400 from the mold core 110, just as a person would typically remove his foot from a shoe. If the shell 300 has flashing where the front and rear mold pieces 210 and 220 meet, as might happen when they do not seal together with sufficient tightness and precision, then that flashing can be trimmed after removal of the mold 200 is removed from around the shoe 400.

FIG. 5 is a cross-section view of toe portion of the shoe 400, mold core 110, and mold 200, taken along line 5-5 of FIG. 3. Between the mold 200 and the mold core 110 are the upper 100 and the shell 300. This view shows that the shell 300 contacts both the interior side 140 and the exterior side 150 of the upper 100 along the bottom periphery rim 160 of the upper 100. In other words, the shell 300 can be said to define a channel along its top periphery rim, in which the bottom periphery rim 160 of the upper 100 is disposed.

FIGS. 6 and 7 are exploded diagrams of two illustrative bonds between the upper 100 and the shell 300 of the shoe 400. In FIG. 6, the upper 100 is a simple one-ply material, such as a leather, which may be treated (e.g., buffed) to remove oils that might interfere with its bonding to the shell 300. The shell 300, when injected in a molten state coheres to the surface of the upper 100 everywhere they are allowed to contact (i.e., on both the interior side 140 and the exterior side 150 in the vicinity of the bottom periphery rim 160 of the upper 100). Such cohering can result from the physical interconnections between the upper 100 and the shell 300. For example, in the vicinity of the bottom periphery rim 160 the upper 100 may have a roughened surface texture (not shown), which enhances the ability of the shell 300 to intermesh with and grip the surface of the upper 100. As another example, in the vicinity of the bottom periphery rim 160 the upper 100 may be a fibrous, porous, or woven material, to which the shell 300 can bond by interspersing among or into fibers, pores, or woven strands (not shown). As yet another example, the upper 100 may comprise perforations (not shown) extending from the interior side 140 to the exterior side 150 along some or all of the bottom periphery rim 160, such that the shell 300 can form in those perforations. In those cases, injecting the shell material 300 in a molten state under sufficiently high pressure can cause the shell material 300 to permeate and interlock with any perforations, fibers, pores, woven strands, or roughened surface features on the upper 100.

In FIG. 7, the upper 100 is a two-ply material of a waterproof membrane 100A on the interior side 140 and a textile 100B on the exterior side 150. As shown in FIG. 7, the upper 100 is folded upon itself. That has two effects. First, it exposes the waterproof membrane 100A on both sides of the upper 100. Second, it creates a bulge on the exterior side 150 of the upper 100. In the areas where the shell 300 contacts the textile 100B during hot injection molding, the shell 300 coheres to the textile 100B, typically by flowing into and subsequently solidifying in or around the pores, woven strands, and/or fibers in the textile 100A. In the areas where the shell 300 contacts the waterproof membrane 100A, the cohering is more like a weld, as the hot shell material melts the waterproof membrane 100A, the two molten materials partially mix, and then solidify bonded together. Moreover, if the fold is in the other direction such that the bulge forms on the interior side, then the heat of the molten shell 300 can melt the waterproof membrane 100A to itself in the interior portion of the fold, so as to retain the upper 100 in its folded position. (Note that the fold can be held in place initially with some minimal adhesive or stitching, which can be easily accomplished as part of the construction of the upper 100.)

The bulge in the upper 100 shown in FIG. 7 can further increase the strength of the bond between the upper 100 and the shell 300. The bulge provides a ledge that resists lateral movement of the cohered surfaces of the shell 300 and the upper 100 across each other over that ledge (i.e., movement of the shell to the right and/or the upper to the left, as shown in FIG. 7). The bulge also deflects lateral forces acting upon the portion where the shell 300 and the upper 100B cohere above the bulge. Although FIG. 7 shows one form of a bulge formed by a fold in the upper 100, bulges of any type, formed by any means, on either or both sides of the upper 100, are also possible.

Note that although FIG. 7 illustrates a folded two-ply material as the upper 100, it is possible to use any number of layers of materials as a multi-layer laminate upper 100, without or without folds, and with or without a waterproof membrane, which could be in any arbitrary layer.

As FIGS. 6 and 7 make clear, the shell 300 can be attached to the upper 100 in a waterproof interface without stitching of the shell 300 to the upper 100. The absence of a stitched attachment reduces the labor and material costs associated with making the shoe 400. Stitching also tends to defeat waterproofing, as threads can act as wicks to transport moisture from one side of a stitched barrier to the other side, unless additional, costly measures are taken to seal and isolate the stitching from possible moisture sources. The shoe 400 avoids those problems. When the upper 100 is a waterproof material, the shoe 400 is a simple-to-construct, waterproof shoe.

The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations can be made to the details of the above-described embodiments without departing from the underlying principles of the invention. For example, just a portion of the shell may be formed and attached to the upper in the manner described above, so as to permit modular shoe designs and constructions. The scope of the invention should therefore be determined only by the following claims, and their equivalents, in which all terms are to be understood in their broadest reasonable sense unless otherwise indicated. 

1. A method for attaching a shoe upper to a shoe shell material by molding, the method comprising: placing the upper on a mold core, which includes a portion resembling a foot and a portion on which the upper fits; providing a flap on the upper, the flap extending along at least a portion of a bottom rim of the upper, the flap having opposing interior and exterior sides; providing a mold around the mold core and the flap so as to define a cavity between the mold and the mold core, the flap extending into the cavity so that both the interior and exterior sides of the flap are exposed within the cavity; and introducing the shell material into the cavity so as to mold the shell material directly around the mold core portion resembling a foot and to cohere the shell material to both the interior and exterior sides of the flap.
 2. The method of claim 1, wherein the step of introducing the shell material into the cavity attaches the shell material to the upper in the absence of stitching between the shell material and the upper.
 3. The method of claim 1, wherein the step of introducing the shell material into the cavity effectuates a substantially waterproof seal between the upper and the shell material.
 4. The method of claim 1, further comprising: folding a portion of the flap upon itself to create a bulge on a side of the flap, thereby resulting in a bulged side of the upper.
 5. The method of claim 4, wherein the step of introducing the shell material into the cavity comprises: cohering the shell material to the bulged side of the upper at a portion of the upper above the bulge.
 6. The method of claim 1, wherein the step of introducing the shell material into the cavity comprises: injecting the shell material into the cavity.
 7. The method of claim 1, wherein the shell material is a thermoplastic material.
 8. The method of claim 1, wherein the step of introducing the shell material into the cavity is performed after the step of providing a mold around the mold core and the flap.
 9. The method of claim 1, further comprising: pressing the mold and the mold core together so as to pinch the upper between the mold and the mold core above the flap.
 10. The method of claim 1, further comprising: attaching an outsole to the shell material.
 11. The method of claim 1, wherein the flap is an integral part of the upper.
 12. A shoe made in accordance with the method of claim
 1. 13. A method for attaching a shoe shell to a shoe upper without stitching the shell to the upper, the upper having opposing interior and exterior sides and a bottom periphery rim for attachment to the shell, the shell having a top periphery rim, the method comprising: cohering the top periphery rim of the shell to portions of both the interior and exterior sides of the upper in proximity to the bottom periphery rim of the upper.
 14. The method of claim 13, further comprising: providing a bulge on one or more sides of the upper along the bottom periphery rim, thereby resulting in one or more bulged sides of the upper, wherein the cohering step comprises cohering the upper rim of the shell to at least one of the bulged sides of the upper at a portion of the upper above the bulge.
 15. The method of claim 14, wherein the providing step comprises: folding a portion of the upper upon itself along at least a portion of the bottom periphery rim, whereby the folded portion creates the bulge.
 16. The method of claim 13, wherein the cohering step comprises: welding the shell to the upper.
 17. The method of claim 16, wherein the welding step comprises: melting the upper; partially mixing the melted upper and the shell together; and solidifying the mixed melted upper and the shell.
 18. The method of claim 13, further comprising: molding the shell.
 19. The method of claim 18, wherein the molding step comprises: providing a mold core including a portion resembling an ankle and a portion resembling a foot; placing the upper on the mold core; providing a mold that defines an interior chamber sized to fit at least a bottom portion of the mold core; placing the mold generally around at least a bottom portion of the mold core, thereby defining a space between the mold core and the mold, such that a portion of the upper proximate to the bottom periphery rim of the upper extends into the space; and introducing into the space a deformable material, whereby the deformable material solidifies, coheres to the portion of the upper extending into the space, and thereby forms the shell.
 20. The method of claim 19, wherein the deformable material is a flowable material.
 21. The method of claim 20, wherein the deformable material comprises a liquid, and the step of providing the deformable material comprises: injecting the liquid into the space.
 22. The method of claim 21, wherein the liquid is a thermoplastic material.
 23. The method of claim 18, wherein the step of introducing the deformable material is performed after the step of placing the mold generally around the mold core.
 24. The method of claim 13 wherein the shell has an interior side facing the mold core and an opposing exterior side, the method further comprising: attaching an outsole to the exterior side of the shell.
 25. A shoe made in accordance with the method of claim
 13. 26. A shoe comprising: an upper having opposing interior and exterior sides and a bottom rim; a shell having an upper rim, the upper rim being cohered to at least portions of both the interior and exterior sides of the upper in proximity to the bottom rim of the upper without stitching of the upper to the shell.
 27. The shoe of claim 26, wherein the upper comprises leather.
 28. The shoe of claim 26, wherein the upper comprises a waterproof layer on the interior side and a textile disposed on the exterior side.
 29. The shoe of claim 26, wherein the waterproof layer is a waterproof coating.
 30. The shoe of claim 26, wherein the waterproof layer is a waterproof membrane.
 31. The shoe of claim 30, wherein the waterproof membrane includes a polytetraflouroethylene layer.
 32. The shoe of claim 26, wherein the upper rim of the shell comprises a channel along the length of the upper rim, and the portions of the upper are disposed at least partially within the channel.
 33. The shoe of claim 26, wherein the shell is formed of a substance, the upper is a fibrous material having fibers, and the substance extends at least partially about at least some of the fibers.
 34. The shoe of claim 26, wherein the shell is formed of a substance, the upper is a woven material having woven strands, and the substance extends at least partially about at least some of the strands.
 35. The shoe of claim 26, wherein the shell is formed of a substance, the upper is a porous material having pores, and the substance extends at least partially into at least some of the pores.
 36. The shoe of claim 26, wherein the shell is formed of a substance, the upper comprises one or more perforations between the exterior and interior sides of the upper in proximity to the bottom rim of the upper, and the substance extends through at least some of the perforations.
 37. The shoe of claim 26, wherein the shell is made of a thermoplastic material.
 38. The shoe of claim 26, wherein the upper comprises: a bulge on one or more sides of the upper along at least a portion of the bottom rim, thereby resulting in at least one bulged side of the upper, wherein the shell extends around the bulge and coheres to a bulged side of the upper on a portion of the upper above the bulge.
 39. The shoe of claim 36, wherein the bulge is formed by a fold of a portion of the upper onto itself along at least a portion of the bottom rim of the upper.
 40. The shoe of claim 26, wherein the shoe is substantially waterproof along the interface of the upper and the shell. 